What lies beneath--discovering the hidden story of plant roots: root growth strategies of wetland plants in northern Ontario along a gradient of growing season length.

Abstract

Root growth strategy can be classified as multi-season (winter-surviving) or single-season (fallsenescing). This study investigated the relationship of wetland plant species with multi-season roots (sMSR) and species with single-season roots (sSSR) to soil temperature across a climatic growing season gradient. Study sites were in Lake Superior Provincial Park and Manitoulin Island. In fall 2013, root ingrowth cores were installed in soil. Root length and shoot dry mass were measured at harvests from spring 2014 to spring 2015. Results showed that soil and air temperature differed by geographic zone; Lake Superior Provincial Park demonstrated lower temperatures than Manitoulin Island. Soil temperature affected root length (positively) and shoot dry mass (negatively). Root growth strategy had a nearly significant relationship with ratio of spring to maximum shoot dry mass—greater for sMSR than sSSR; and a significant relationship with relative late season shoot dry mass change—decreasing for sMSR and increasing for sSSR.